N-甲基-D-天冬氨酸和γ-氨基丁酸对蝙蝠下丘薄片诱发电活动的影响

在47只不同年龄的蝙蝠的86张中脑下丘的冠状薄片上 ,电刺激外侧丘系 ,记录到149例下丘中央核的诱发场电位。分别观察了微电泳N -甲基 -D -天冬氨酸 (NMDA)、2 -氨基 -5 -磷酸戊酸 (2 -APV)、γ -氨基丁酸 (GABA)、荷包牡丹碱 (bicuculline)等对下丘中央核诱发场电位幅度的影响。实验结果表明 ,外侧丘系对蝙蝠中脑下丘中央核的传入影响可能主要由GABA、Glu以及GABAA 、NMDA受体所介导 ;在不同的年龄组 ,对NMDA及GABA等反应的诱发单位比例基本一致、反应幅度无显著差异。鉴于蝙蝠整体实验的结果表明 ,中脑下丘中央核听反应神经元的GA BA能输入在出生后早期存在显著的发育过程。根据对诱发电位幅度的分析结果 ,推测这种GABA能输入在出生后早期的增长可能源于高位中枢的下行投射。     

N-甲基-D-天冬氨酸和γ-氨基丁酸对蝙蝠下丘薄片诱发电活动的影响

在４７只不同年龄的蝙蝠的８６张中脑下丘的冠状薄片上,电刺激外侧丘系,记录到１４９例下丘中央核的诱发场电位。分别观察了微电泳Ｎ－甲基－Ｄ－天冬氨酸（ＮＭＤＡ）、２－氨基－５－磷酸戊酸（２－ＡＰＶ）、γ－氨基丁酸（ＧＡＢＡ）、荷包牡丹碱（ｂｉｃｕｃｕｌｌｉｎｅ）等对下丘中央核诱发场电位幅度的影响。实验结果表明,外侧丘系对蝙蝠中脑下丘中央核的传入影响可能主要由由ＧＡＢＡ、Ｇｌｕ以及ＧＡＢＡＡ、ＮＭＤＡ受     

水杨酸钠对小鼠下丘核神经元GABAα、NR1表达及听反应的影响

目的:探讨水杨酸钠给药对小鼠下丘核神经元GABAα、NR1表达及听反应的影响。方法:实验将36只成年健康昆明小鼠分三组(n=12):A组:对照组;B组:水杨酸钠给药组(450mg.kg-1.d-1);C组:水杨酸钠(450mg.kg-1.d-1)+利多卡因(10mg.kg-1.d-1)组。各组均经腹腔注射给药,A组给以同等剂量的生理盐水,所有动物自由饮食。给药15 d后进行检测。采用RT-PCR技术检测小鼠下丘核区GABAα、NR1mRNA的表达;采用细胞外电生理记录技术研究下丘核区神经元在水杨酸钠给药后强度-发放率函数、强度-潜伏期函数和频率调谐曲线的变化。结果:①水杨酸钠组的下丘核区GABAαmRNA表达较对照组明显降低(P<0.05);水杨酸钠+利多卡因组与对照组比较无显著性差异(P>0.05);水杨酸钠组NR1mRNA表达较对照组明显升高(P<0.01),水杨酸钠+利多卡因组与对照组比较有显著性差异(P<0.05);②水杨酸钠给药后发放率和潜伏期函数呈非单调性改变,而神经元的调谐曲线从狭窄型向宽阔型转变;③水杨酸钠+利多卡因组发放率和潜伏期函数呈非单调性改变,而神经元的调谐曲线从狭窄型向宽阔型转变例数显著减少(P<0.05,P<0.01)。结论:①水杨酸钠引起实验小鼠下丘核GABAαmRNA表达下调,同时又使小鼠下丘核NR1mRNA表达增高;②水杨酸钠给药后发放率和潜伏期函数呈非单调性改变,而神经元的调谐曲线从狭窄型向宽阔型转变③利多卡因有逆转水杨酸钠给药后发放率和潜伏期函数呈非单调性改变和神经元的调谐曲线从狭窄型向宽阔型转变的作用。     

Mechanisms of experience-dependent plasticity in the auditory localization pathway of the barn owl

Sound localization is a computational process that requires the central nervous system to measure various auditory cues and then associate particular cue values with appropriate locations in space. Behavioral experiments show that barn owls learn to associate values of cues with locations in space based on experience. The capacity for experience-driven changes in sound localization behavior is particularly great during a sensitive period that lasts until the approach of adulthood. Neurophysiological techniques have been used to determine underlying sites of plasticity in the auditory space-processing pathway. The external nucleus of the inferior colliculus (ICX), where a map of auditory space is synthesized, is a major site of plasticity. Experience during the sensitive period can cause large-scale, adaptive changes in the tuning of ICX neurons for sound localization cues. Large-scale physiological changes are accompanied by anatomical remodeling of afferent axons to the ICX. Changes in the tuning of ICX neurons for cue values involve two stages: (1) the instructed acquisition of neuronal responses to novel cue values and (2) the elimination of responses to inappropriate cue values. Newly acquired neuronal responses depend differentially on NMDA receptor currents for their expression. A model is presented that can account for this adaptive plasticity in terms of plausible cellular mechanisms. Accepted: 17 April 1999     

Tectal and Related Target Areas of Spinal and Dorsal Column Nuclear Projections in Hedgehog Tenrecs

The terminal distributions of spinal and dorsal column nuclear projections to tectum, pretectum, and central gray of hedgehog tenrecs (Echinops telfairi and Setifer setosus) were investigated using anterograde axonal flow and various tracer substances. In the inferior colliculus, the densest and most extensive mesencephalic projections were found within the pericentral regions. One target area, referred to as the external portion of the inferior colliculus, was represented as a semicircle of grain patches lateral and caudal to the central nucleus. This region received somesthetic afferents from the dorsal column nuclei and from spinal segments at various levels. In contrast, after high cervical injections, the pericentral portion dorsomedial to the rostral half of the central nucleus was labeled almost exclusively. This area of labeling was distinct from the labeling in the central gray and might be best compared with the intercollicular zone in other species. The superior colliculus received projections predominantly from the high cervical cord; minor projections also arose from lumbar spinal segments and the dorsal column nuclei. The terminal field covered roughly the caudal half of the colliculus and involved the stratum griseum intermediale in a patch-like fashion. Some labeling was also found in the stratum griseum profundum and in the stratum griseum superficiale. Other than in the colliculi, weak pretectal projections were observed following dorsal column nuclear injections, while the nucleus of Darkschewitsch was labeled best following lumbosacral injections. All mesencephalic target areas were labeled consistently on the contralateral side, while their ipsilateral side was involved to a varying degree: The relatively most prominent ipsilateral labeling was seen in the central gray, being roughly similar on both sides; scarcely any labeling was noted in the ipsilateral superior colliculus. Tectal injections of retrograde tracer, in addition, revealed a considerable number of labeled neurons in a relatively cell-poor region immediately ventral to the high cervial dorsal horn. This region might correspond to the lateral cervical nucleus, an aggregation of neurons that so far has only been demonstrated in higher mammals.     

猫下丘中央核GABA能神经元年龄相关变化

目的比较研究猫下丘中央核(CIC)GABA能神经元年龄相关变化,探索老年个体听力下降的神经机制。方法Nissl染色显示下丘神经元,免疫组织化学ABC法显示γ-氨基丁酸(GABA)免疫阳性神经元。光镜下观察、拍照,对神经元和GABA能神经元分别计数并换算成密度,测量GABA能神经元直径取平均值。结果GABA阳性反应神经元、阳性纤维及其终末在青年猫及老年猫下丘中央核均有分布。与青年猫相比,老年猫下丘中央核神经元及GABA能神经元密度均显著下降(P<0.01),GABA能神经元下降幅度较大;GABA能神经元胞体直径明显减小(P<0.01),阳性反应明显减弱。结论在衰老过程中猫下丘神经元尤其是GABA能神经元有显著丢失现象,提示GABA能神经元显著减少导致下丘兴奋性和抑制性神经递质之间的平衡失调,可能是引起老年个体听觉功能衰退的重要原因。     

Contribution of GABAA receptor-mediated inhibition to the determination of the velocity tuning of low pass-tuned neurons of the Superior Colliculus

The participation of intrinsic inhibitory networks in providing the velocity selectivity of neurons of the superior colliculus (SC) of the Syrian hamster was tested using iontophoretic application of bicuculline methiodide, a GABA_A receptor competitive antagonist. The impulse activity of 22 low pass-tuned (LP) cells was recorded extracellularly. Following application of bicuculline, 10 cells exhibited an increase in the velocity selectivity, while the other 12 units showed decreases in their tuning. We assume that SC intrinsic inhibitory networks contributing to the velocity tuning of neurons of this structure are driven in a dissimilar way by afferent volleys arriving from the retina through “fast” Y and “slow” W channels. Neirofiziologiya/Neurophysiology, Vol. 39, Nos. 4/5, pp. 385–387, July–October, 2007.     

电刺激大马蹄蝠听皮层对下丘神经元听觉敏感性的影响

实验在１２只大马蹄蝠上进行。用常规电生理学方法研究了电刺激听皮层对下丘２１２个神经元的听反应的影响,结果表明,有３２个神经元的听反应被抑制,１９个神经元的听反应褐易化。     

大鼠上丘到外膝体P－物质投射的机能

已知大鼠外膝体内有中脑上丘来的含Ｐ－物质的神经末梢,其机能不明。在离休的大鼠外膝体脑片上用单电极电压箝位的方法研究了Ｐ－物质对外膝体神经元电压依赖性离子通道的作用。结果表明,Ｐ－物质可以使静息膜去极化,并降低膜电导。这提示Ｐ－物质抑制了线性钾漏电流。此外,Ｐ－物质还抑制去极化激活的慢失活的钾电流、低阈值钙电流和超极化激活的内向整流（Ｈ或Ｑ）电流。Ｐ－物质还可能抑制早钾（Ａ）电流。因此,Ｐ－物质在外膝体视觉信号传递中的作用是使外膝体神经元从爆发反应方式或振荡状态转化为中继反应方式,易化突触传递,使视网膜的视觉信号忠实地传递到大脑皮层。     

Auditory properties of the superior colliculus in the horseshoe bat,Rhinolophus rouxi

Summary Auditory response properties were studied in the superior colliculus (SC) of the echolocating horseshoe bat Rhinolophus rouxi, a long CF-FM bat, by the use of stationary, dichotic stimuli.The most striking finding in the horseshoe bat was an enormous overrepresentation of neurons with best frequencies in the range of the constant frequency component of the species specific echolocation call (72% of the auditory neurons). These neurons had response thresholds as low as 0 dB SPL and were narrowly tuned with Q_{10 dB} — values up to 400, just as in the nuclei of the primary auditory pathway in this species. This overrepresentation may suggest the importance of the superior colliculus in the context of echolocation behavior.While noise stimuli were not particularly effective, other auditory response properties were similar to those described in other mammals. 65% of the SC neurons in the horseshoe bat responded only to monaural stimulation of one ear, primarily the contralateral one. 32% of the neurons received monaural input from both ears. The proportion of neurons responsive to ipsilateral stimulation (41%) was rather high. Mean response latency was 8.9 ms for contralateral stimulation.A tonotopic organization is lacking, but high-frequency neurons are less frequent in rostral SC.Abbreviations CF constant frequency component of echolocation call; - >CF frequencies above range of CF-component - FM frequency modulated component of echolocation call - <FM frequencies below range of FM-component - RF resting frequency of an individual bat - Rh.r. Rhinolophus rouxi - SC superior colliculus     

Neural modulation in inferior colliculus and central auditory plasticity

The neural modulation in central auditory system plays an important role in perception and processing of sound signal and auditory cognition. The inferior colliculus (IC) is both a relay station in central auditory pathway and a sub-cortical auditory center doing the sound signal processing. IC is also modulated by the descending projections from the cortex and auditory thalamus, medial geniculate body, and these neural modulations not only can affect ongoing sound signal processing but can also induce plastic changes in IC.     

2，5－己二酮对大鼠视束纤维和视上丘细胞电生理特性的影响

应用复合动作电位记录技术研究了２,５－己二酮对大鼠视束大纤维（Ｔ１）和中纤维（Ｔ２）以及视上丘（ＳＣ）Ｃ２细胞电生理特性的影响。结果表明：２,５－己二酮使视束Ｔ１和Ｔ２轴突的传导速度降低,反应波形的幅度下降、上升时间延长、宽度增加、基强度减小。从Ｔ２到Ｃ２的突触延搁增加,Ｔ２和Ｃ２的恢复功能曲线有明显的超常兴奋性,相对不应期减小。２,５－己二酮对Ｔ２和Ｃ２细胞的电生理特性有选择性影响。     

持续与间断噪声前掩蔽条件下小鼠下丘神经元的不同反应模式

有关听中枢神经元纯音前掩蔽效应的神经表征已进行了大量研究,但是,噪声前掩蔽尤其是间断噪声前掩蔽效应的神经表征却鲜有报道。本研究观察了自由声场条件下,昆明小鼠下丘神经元在持续与间断噪声前掩蔽条件下对纯音探测声的反应。共记录到96个下丘神经元,测量了其中51个神经元在不同声刺激条件下的强度一放电率函数。结果显示,掩蔽声强度分布较广（探测声阈下21dB至阈上19dB之间）。在将近一半的神经元中,间断噪声的前掩蔽效应比持续噪声强（Ⅰ型,45．10％,P〈0．001）,但也有少数神经元其间断噪声的掩蔽效应较持续噪声的弱（Ⅲ型,17．65％,P〈0．001）,部分神经元无显著性差异（Ⅱ型,37．25％,P〉0．05）。无论Ⅰ型还是Ⅲ型神经元,持续噪声和间断噪声均在探测声强度较低时产生较强的抑制效应,随着探测声强度的升高,抑制效应逐渐降低（P〈0．001）;同时,持续噪声和间断噪声之间前掩蔽效应差异亦不复存在（P〉0．05）。此外,当掩蔽声由持续噪声换为间断噪声后,部分Ⅰ型神经元掩蔽时相的类型发生转变,其中最主要的转变为由前期抑制转变为均衡抑制（53．85％,7／13）。对下丘神经元声反应的时间域以及强度域,持续与间断噪声具有分化性前掩蔽效应,提示噪声前掩蔽并非简单的神经元发放压抑源,某些主动性神经调制机制可能参与了噪声条件下时相声信息的编码过程。     

Remapping for visual stability

Visual perception is based on both incoming sensory signals and information about ongoing actions. Recordings from single neurons have shown that corollary discharge signals can influence visual representations in parietal, frontal and extrastriate visual cortex, as well as the superior colliculus (SC). In each of these areas, visual representations are remapped in conjunction with eye movements. Remapping provides a mechanism for creating a stable, eye-centred map of salient locations. Temporal and spatial aspects of remapping are highly variable from cell to cell and area to area. Most neurons in the lateral intraparietal area remap stimulus traces, as do many neurons in closely allied areas such as the frontal eye fields the SC and extrastriate area V3A. Remapping is not purely a cortical phenomenon. Stimulus traces are remapped from one hemifield to the other even when direct cortico-cortical connections are removed. The neural circuitry that produces remapping is distinguished by significant plasticity, suggesting that updating of salient stimuli is fundamental for spatial stability and visuospatial behaviour. These findings provide new evidence that a unified and stable representation of visual space is constructed by redundant circuitry, comprising cortical and subcortical pathways, with a remarkable capacity for reorganization.     

2，5－己二酮对大鼠视束纤维和视上丘细胞电生理特性的影响

应用复合动作电位记录技术研究了２,５－己二酮对大鼠视束大纤维（Ｔ１）和中纤维（Ｔ２）以及视上丘（ＳＣ）Ｃ２细胞电生理特性的影响。结果表明：２,５－已二酮使视束Ｔ１和Ｔ２轴突的传导速度降低,反应波形的幅度下降、上升时间延长、宽度增加、基强度减小。从Ｔ２到Ｃ２的突触延搁增加,Ｔ２和Ｃ２的恢复功能曲线有明显的超常兴奋性,相对不应期减小。２,５－己二酮对Ｔ２和Ｃ２细胞的电生理特性有选择性影响。     

Demonstration of retinal afferents in the RCS rat,with reference to the retinohypothalamic projection and suprachiasmatic nucleus

In the Royal College of Surgeons (RCS) rat, characterized by inherited retinal dystrophy, retinal projections to the brain were studied using anterograde neuronal transport of cholera toxin B subunit upon injection into one eye. The respective immunoreactivity was found predominantly contralateral to the injection site in the lateral geniculate nucleus, superior colliculus, nucleus of the optic tract, medial terminal nucleus of the accessory optic tract, and bilateral hypothalamic suprachiasmatic nuclei. Although terminal density was somewhat reduced in dystrophic rats, the projection patterns in these animals appeared similar to those seen in their congenic controls and were comparable to the visual pathways described for the rat previously. In dystrophic rats, the number of cell bodies exhibiting immunoreactivity to vasoactive intestinal polypeptide, viz. a population of suprachiasmatic neurons receiving major retinohypothalamic input, was reduced by one-third, and some differences were observed in the termination pattern of the geniculohypothalamic tract, as revealed by immunoreactivity to neuropeptide Y in the suprachiasmatic nucleus.This study was supported by grants from the DFG (Re 644/2-1) and the NMFZ, Mainz (to S.R.).     

Neuroglobin基因体内转染对水杨酸钠给药后小鼠下丘核神经元听反应的影响

实验以48只成年健康昆明小鼠为实验对象,研究GeneJamer转染试剂介导的neuroglobin(NGB)基因体内转染对水杨酸钠给药后小鼠下丘核区听反应的影响。实验分4组,每组12只。A1组:对照组1(阴性对照,将GeneJamer转染试剂6μl和pEGFP-C12μg混合后注入下丘核脑区);A2组:对照组2[阳性对照,将GeneJamer转染试剂(6μl)和pEGFP-NGB(质粒载体pEGFP-C1与NGB基因全编码序列构建的重组子2μg)混合后注入下丘核脑区];B组:水杨酸钠给药组(450mg/kg·d-1)+pEGFP-C1;C组:水杨酸钠(450mg/kg.d-1)+pEGFP-NGB组。以直接注射法将GeneJamer转染试剂和重组质粒pEGFP-NGB混合后注入小鼠下丘核区。采用RT-PCR和Westernblot技术检测小鼠下丘核区NGBmRNA和蛋白的表达;采用细胞外记录技术,研究小鼠下丘核区神经元在水杨酸钠给药后转染重组质粒pEGFP-NGB对强度-发放率函数(刺激声强与实验鼠下丘核区神经元在接受声刺激所产生的电发放的关系曲线)、强度-潜伏期函数(刺激声强与实验鼠下丘核区神经元在接受声刺激至产生电发放潜伏期之间的关系曲线)和频率调谐曲线(实验鼠下丘核区神经元在各个频率纯音刺激下起反应的阈值绘制的曲线)的影响。实验观察到:(1)经GeneJamer转染试剂介导NGB基因可有效地转染小鼠下丘核区脑组织并得到表达。(2)水杨酸钠给药后神经元的强度-发放率函数曲线升高。对照组A1、A2各项指标进行比较均无统计学意义。对照组A1、A2和水杨酸钠+pEGFP-NGB组神经元的强度-发放率函数以非单调型(随刺激强度增加时,发放率表现为先降后升呈“V”形或“U”形)为主,分别占74.6%、72.2%和59.3%,水杨酸钠给药组以不规则型强度-发放率函数为主,占47%,与对照组A1、A2和水杨酸钠+pEGFP-NGB组比较,有显著性差异(P<0.01、P<0.01、P<0.05)。(3)水杨酸钠给药后神经元的强度-潜伏期函数曲线降低。对照组A1、A2各项指标进行比较均无统计学意义。水杨酸钠给药组以非单调型强度-潜伏期率函数为主,与对照组A1、A2和水杨酸钠+pEGFP-NGB组比较,有显著性差异(P<0.01、P<0.05)。(4)A1和A2对照组听反应神经元的调谐曲线,Q-10dB值均大于5.00,其调谐曲线为狭窄型。记录水杨酸钠给药组72个听神经元的调谐曲线,有53个神经元的Q-10dB值小于5.00,Q-10dB值最小为2.12,其调谐曲线为宽阔型;其余19个神经元的Q-10dB值大于5.00,属于狭窄型调谐曲线。水杨酸钠+pEGFP-NGB组67个听神经元的调谐曲线,有12个神经元的Q-10dB值小于5.00,Q-10dB值最小为2.87,其调谐曲线为宽阔型,其它的神经元的值大于5.00。它们的调谐曲线均属狭窄型。以上结果提示外源性NGB基因在水杨酸钠给药后小鼠下丘核区局部高表达,提示GeneJamer转染试剂介导NGB体内转基因治疗水杨酸钠引起的下丘核区的损伤的方法是可行的。实验小鼠转染NGB基因后可逆转因水杨酸钠给药引起的强度-发放率函数曲线升高以及强度-潜伏期函数曲线降低,并可逆转水杨酸钠引起的部分听神经元对声刺激强度的编码类型。     

N-甲基-D-天冬氨酸(NMDA)及荷包牡丹碱对不同年龄蝙蝠下丘神经元听反应的影响

分别对出生后第２周和第４周的中华鼠隔蝠中脑下丘中央核１２１个听神经元进行了考察,同时与成年动物进行比较。结果表明,微电泳ＮＭＤＡ对下丘中央核绝大部分听神经元具有易化性影响,表现为听反应脉冲发放率增加,反应阈值下降,频率谐曲线增宽。     

电刺激蝙蝠小脑对下丘神经元听反应的影响

实验在34只长翼蝠(Miniopterus schrebersi)上进行.使用玻璃微电极在中脑下丘中央核记录听神经元电反应.电刺激点分别位于小脑蚓部、半球和绒球小结叶共观察了515个对超声刺激产生反应的下丘听神经元.当电刺激小脑时,有171个(占33.2%)神经元听反应受到影响.其中126个(占24.5%)表现为抑制,45个(8.7%)表现为易化.抑制效应表现为神经元所反应放电频数降低和反应潜伏期延长.易化效应则相反.抑制与易化潜伏期一般都在6毫秒以上.抑制效应与电刺激强度、声刺激强度以及声刺激和电刺激的时间间隔有关.抑制和易化性影响都是双侧性的.     

Age‐dependent failure of axon regeneration in organotypic culture of gerbil auditory midbrain

Inferior colliculus (IC) slice cultures from postnatal (P) day 6–8 gerbils exhibit axonal regeneration across a lesion site, and these regrowing processes can form synapses. To determine whether regenerative capacity is lost in older tissue, as occurs in vivo, slices from P12–21‐day animals were grown under similar conditions. While these cultures displayed a near complete loss of neurons over 6 days in vitro, glutamate receptor antagonists (AP5 and/or CNQX) significantly enhanced survival, particularly at P12–15. In contrast, several growth factors or high potassium did not improve neuron survival. Therefore, axonal regeneration was assessed following complete transection of the commissure in AP5/CNQX‐treated IC cultures from P12 animals. Neurofilament staining revealed that transected commissural axons survived for 6 days in vitro, but only a few processes crossed the lesion site and these axons did not extend into the contralateral lobe. In contrast, there was robust axonal sprouting and growth within one lobe of the IC, remote from the lesion site. When P6 and P12 tissue was explanted onto a coated substrate, the P6 axons grew onto the substrate, but the P12 axons were seemingly prevented from reaching the substrate by a veil of nonneuronal cells. Coculture of the IC and one of its afferent populations, the lateral superior olive, provided a similar finding, indicating that failure to regenerate was a general property at the age examined. These data show that neuron survival is not sufficient to permit axon regeneration at P12, and suggest that P12 lesion sites manufacture a prohibitive substrate since process outgrowth is blocked specifically at the commissure transection. © 1999 John Wiley & Sons, Inc. J Neurobiol 41: 267–280, 1999